program ConvexOrNot;

{$APPTYPE CONSOLE}

uses
  SysUtils;
var
  N,i,a: integer;
  massx, massy: array of integer;
  fin: textFile;

begin
  assignFile(fin,'input.txt');
  reset(fin);
  read(fin, N);
  setLength(massx,N-1);
  setLength(massy,N-1);
  for i:=0 to (2*N-1) do
  begin
    if (i mod 2=0) then
    begin
      read(fin, massx[i div 2]);
    end
    else
    begin
      read(fin, massy[i div 2]);
    end;
  end;
  massx[2*N]:=massx[0];
  massy[2*N]:=massy[0];
  a:=0;
  for i:=0 to 2*N-2 do
  begin
    if (massx[i+1] - massx[i]) * (massx[i+2] - massx[i+1]) + (massy[i+1] - massy[i]) * (massy[i+2] - massy[i+1]) < 0 then
    begin
      a:=a+1;
    end;
  end;
  if (a=0) then
  begin
    writeln('Convex.');
  end
  else
  begin
    writeln('Not convex.');
  end;
  readln;
  closeFile(fin);
end.
